论文部分内容阅读
当我们欣赏墙上的精彩条幅时,站在何处视角最大?奇妙而有趣的是——“尺规作图”能帮我们精确定位。题目:(湘教版《义务教育教科书·数学》七年级上册第95页)如图1,AB是教室里挂的一幅条幅,直线CE是水平视线,小刚在点C观察它,△ABC的∠C称为视角。试问:C、D、E三点处的视角哪个最大?是不是离AB越近视角越大?本题的实际背景在现实生活中很常见。把它抽象为数学问题时,很值得思考。但对七年级学生来说只能是定性思考,下面展示学生在课堂中的探究:
When we enjoy the wonderful banner on the wall, where to stand the most perspective? The curious and interesting is - “rule rule mapping ” can help us pinpoint. Subject: (Xiang version of “compulsory education textbook mathematics” seventh grade on page 95) Figure 1, AB is a banner hanging in the classroom, the line of sight is a straight line CE, Xiaogang observed at point C, △ ABC The ∠ C is called perspective. Ask: C, D, E three point of view which is the largest? Is it closer to the closer to the perspective of AB? The actual background of the problem is very common in real life. When abstracting it into a mathematical problem, it is worth thinking about. But for the seventh grade students can only be qualitative thinking, the following shows the students explore in the classroom: